Pattern-copying machine



L s. TOPHAM- PATTERN COPYING CHINE May 21, 1929..

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PATTERN COPYING MACHINE Original Filed Jan. 18. 1922 11 Sheets-Sheet 8 WVE/VTUR May 21, 1929. E. TOPHAM I PATTERN COPYING MACHINE Uriginal Filed Jn. 18. 1922 11 Sheets-Sheet 9 y 21, 1929- L. E. TOPHAM PATTERN COPYING MACHINE Original Filed Jan. 18. 1922 ll Sheets-Sheet 10 53 g 15 C C rrrL (Ill-P Ill UFFLL-r rrrC May 21, 1929. L. E. TOPHAM PATTERN COPYING MACHINE 11 Sheets-Shet 11 Original Filed Jan. 18. 1922 //v VEN 44M 6? x za Patented May 21, 1929.

UNITED STATES PATENT OFFICE.

LAURENCE E. TOPHAM, OF WENHAM, IJIASSACHUSETTS, .ASSIGNOR T0 .UNITED SHOE MACHINERY CORPORATION, OF PATERSON. NEW JERSEY, A CORPORATION OF NEW JERSEY.

PATTERN-COPYING MACHINE.

Application filed January 18, 1922, Serial No. 530,214. Renewed June 11, 1928.

This invention relates to pattern copying machinery and is herein disclosed as embodied in a last lathe designed especially to be used in cutting last parts, as distinguished from entire lasts.

The separate cutting of last parts has been proposed before, and the prior inventions directed thereto have been characterized by much ingenuity and have offered considerable promise. It is a primary object of the present invention to advance this branch of the art still further by providing a number of improvements of a distinctly practical nature which. will further the production of individual interchangeable last parts on a commercial basis, While preserving fully the important advantages secured by the prior 1nventions.

A fundamental requirement of the general problem of last part production is that the parts must be truly interchangeable, otherwise the advantages of the separately formed last part and of the separable last are not fully secured. In one aspect the problem is to obtain accuracy of cut. Accuracy is of course a desideratum in any last cutting, but for various reasons is sacrificed to a considerable extent in the production of ordinary lasts. In the production of last parts, accuracy is vital to enable the parts to fit properly when put together.

Inaccuracy of cut arises under heretofore existing practice in a variety of ways. The swing frame in ordinary use is, roughly, inches square; the model and work are suspended in it near the two lower corners; a pressure of 20 pounds on one corner will spring it 1/4 inch, and the pressures exerted on it by the model wheel at the times of its reversals of movement distort it appreciably, causing corresponding inaccuracy of cut. It is also so heavy and of such great moment of inertia that the jar of reversal of movement complicates still further the inaccuracy due to its bending. This sets a very low upper limit to the speed at which the machine can be run. Indeed, if a number of lasts are cut on the ordinary last lathe at speeds ranging from 10 to R. P. M. they will all be recognizably different. These machines are actually run at a compromise speed of 30 R. P. M. or less and even this speed sacrifices accuracy to a noticeable extent.

These difficulties of non-rigidity and jar can be ameliorated by a swing frame of short radius, and consequent small moment of inertia and increased stiffness. But such swing frames have never come into use because of their aggravation of a further difliculty introduced by the necessity of Width grading. It is necessary for successful width grading that the axes of the model, work, model Wheel and cutter be at all times in a common plane. The plane itself may move, but they must all stay in it. This plane will move where a swing frame is used, owing to the curvilinear movement of the model and work; the width grading movement of the model Wheel (or cutter) in the ordinary machines is in a straight line, and consequently cannot remain in this swinging plane. The long radius of the ordinary swing frame permits only a tolerable performance in spite of the flatness of its arc of swing, and a short swing frame would, by itself, be quite impractical. Attempts have been made to solve this difiiculty by the slide frame, which moves in a plane, but this has been found to cause inaccuracy through sluggishness.

Accordingly in this aspect of the invention, its object is to provide a swing frame of short radius with its attendant advantages which will be practical and permit really accurate width grading. Assuming the possibility of a solution of this problem as stated, it must be recognized that there is a limit to the shortening of the swing frame radius. There must be a substantial mechanical axis, in the interest of stiffness, and there must be some three inches or so of clearance between the frame and the axes of the model and work to permit the rough block to rotate. The present invention has practically secured this minimum, providing, as herein illustratively exemplified, a swing frame of only 7 inches radius of swing, with half of its mass located at the center, an important feature of it being a single heavy square shaft in the axis of swing, on which the model and block carriers are mounted. This frame is practically undistortable and can be successfully vibrated very much more rapidly in view of its small moment of inertia than frames of former types.

The width grading problem is met by providing a mechanism for handling the gradin instrumentality (here the model wheel which causes it to follow the plane containing the model. work and cutter wherever it moves, In the illustrated machine, this is accomplished by moving the model wheel in a direction transverse to the direction of ordinary width grading movement to keep it in this plane.

Another cause of inaccuracy under ordinary practice is due to the presence of a train of gears between the model and work. As lhe model wheel rolls over the cone of the model any existing backlash reverses so that the parts mo re to the other extremity of their possible lost motion, and a relative discontinuity of movement between the model and block results. In ordinary last cutting this is ignored because it causes no prominent discontinuity on the complete last itself but it is intolerable in the cutting of a last part be- :ause it would cause a noticeable and adventitious discontinuity between the contours of the joint surfaces of two separately formed last parts. The present invention meets this difiiculty by providing a novel organization comprising, as shown herein. a single unitary drive spindle arranged to drive directly both the model and work. This has brought with it an ancillary feature of reorganization of the length grading mechanism due to the fact that the spindle must engage broad and roomy parts of the model and work, where a reliable driving grip can be secured. such parts being conveniently the joint surfaces. whence the cutter and model wheel must move in opposite directions.

Another phase of the matter of accuracy, having a particular bearing on the question of interchangeability of individual last parts is the imperative necessity of accurately shaping and placing the oint surfaces of the last parts in respect to the foot form contour. According to the present invention. this is accomplished in the illustrated machine by providing the said single unitary drive spindle with dogs constructed to fit and cooperate with prepared surfaces on the model and block having a definite relation to the external contour of the last or to some other detern'iining feature thereof. As herein disclosed, the prepared surface is the joint surface itself. Thus there is an unvarying relation between the fundamental gage points of the machine and the foot form, so that the relation between the foot form and the joint surface is likewise invariable.

Another feature of the invention consists in a novel construction of the length and width grading mechanism so that they can be conveniently controlled continuously by the operator in order to grade the lasts throughout irregularly according to any predetermined plan. Advantageously the setting handles are ar 'anged conveniently to the operators two hands and pointers are provided for the setting apparatus which more relatively over a chart so that the OPOI'ZitOI can continuously control the grading at all times.

Another feature of the invention relates to the construction of the width grading mechanism itself. It is customary. in width grading. to increase the girths of the lasts a uniform amount for each size. This causes the actual grading factor to vary, throughout the series. and the movement of the setting element is even more irregular, not being even proportional to the grading factor owing to the peculiar nature of the mechanism. In order to secure an equicrescent setting scale in the machines known prior to the present invention. the mechanism was changed in such a way as to destroy the pantographic nature of the reproduction, only the girth measurements being preserved. The present invention deals with this di'liiculty by providing a width grading mechanism having an equicrescent setting scale but without any consequent impairment of the pantographic nature of the reproduction aceomplished thereby.

These and other features of the invention including certain details of construction and combinations of parts will be described as embodied in an illustrative machine and pointed out in the appended claims.

Referring to the accompanying drawmg Fig. 1 is a front elevation.

Fig. 2 is a plan.

Fig. 3 is an end elevation.

Fig. 4 is a section on line .l l of Fig. 2. Fig. 5 is a detail of the swing frame. Fig. 6 is a detail of the model and dog.

Fig. 7 is a detail of the face plate and dog.

Fig. 8 is a perspective of a preferred grading arrangement.

Fig. 9 is a section on line. 99 of Fig. 1.

Fig. 10 is a detail of the width g'ading mechanism.

Fig. 11 is a diagram illustrating the swing frame action.

Fig. 12 is a diagram illustrating the width grading mechanism.

Fig. 13 illustrates the formation of the grading chart.

Fig. 14 shows the swing frame equipped with offset dogs. y

Figs. 15. 16, 17 are details of the offset dogs.

Fig. 18 is a diagram illustrating the practice of backing off the fan board.

Fig. 19 is a diagram of the width grading mechanism.

The frame 10 of the machine carries two longitudinal V-shaped guides 1214; along its front and a flatguide 1.6 along its rear. The model wheel carriage 18 slides on the guides 12, 16, and the cutter carriage 2O slides on the guides 14. 16. An intermediate carriage 22 slides on the guides 12, 16 for purposes which will be explained later. The carriages E20 and 22 are driven in opposite directions by a right and left hand screw 24. mounted in a bracket 26011 the main frame and driven by ill) a spiral gear 28. This gear is driven by a spiral gear not shown, but mounted on the shaft 30, parallel to and behind the worm wheel 32, which is driven by the worm shaft 34 in the well-known manner. The sh: ft 34 is driven from the pulley 36 on the shaft -38 which extends clear through the machine and is driven by the pulley from the stub shaft 42. by a motor not shown.

Mounted in bearings it; on the ends of the machine (which. bearings also carry the shaft 38) is the swing frame l8. This frame is designed for minimum moment of inertia and maximum resistance to twisting stress. It is preferably constructed as a square bar mounted on trunnions 49 in the bearings &6. See Figs. 5 and 14. This bar carries at about its middle portion a frame 50 adjustable along the square bar, though ordinarily left permanently in a determined position. This frame carries a gear box and a pedestal 54, in which is mounted a shaft 56. This shaft has on its opposite ends specialized face plates 58, 60. These are advantageously made in the form of an ordinary face plate 62 with crossed keys 64 projecting from it. On these keys is mounted a special dog 66, by screws 67, fitting the keys on one side and on the other shaped to the exact angle and form of the joint surface of the last part 68 to be turned (and of the model The machine shown is arranged to cut last parts for lasts of the type disclosed in United States Letters Patent No. 1,660,478, granted Feb. 28. 1928. on application of G. P. S. Cross. The parts of such a last are both faced with metal plates, and a plate 69 may be advantageously placed in the machine between the dog 66 and. the model 70 or last part 68, of thickness equal to that of a last part plate. so that the face of the dog corresponds exactly to the face on the complementary 1st part. This structure simplifies the adjustment of the gage points of the machine. The dog 66 is equipped with. studs 71 which tit corresponding holes prepared in a preferably plane surface on the model or block, so that exact correspomlence between last parts can be secured. The plane surface is preferably that of the joint between the parts.

Slidahly u'iounted on the square bar near the ends are two dog carrying frames 72. 74-. These frai'nes are adjusted along the square bar by screws 76, 7 8. threaded into them and mounted, in any desired way on the swing frame to permit rotation but not longitudinal movements. The dogs 80. 82 are thus brought up to and embedded in the model and work. The model and work are held in the machine solely by the pressure between the dogs. The adjusting screws are clamped by wing nuts 79.

The drive (see Fig. 4) is effected from the shaft 88 as follows :The shaft has on its left end a pinion 8% which drives a train 86, 88

n'iounted in the left bearing plate 46. This train drives a gear 90 mounted to turn on the axis of the swing frame 48. This drives a gear 92 mounted on the swing frame, which through its shaft 9 1 drives the splined gear 96 mounted in the frame 72 which in turn drives the model dog 84') through a gear 98. The dog 80 is round and its drive is theoretically unnecessary, but saves wear on the model. As shown it cannot drive the model. The shaft 9-;l: extends from the gear 92 through the frame 79. into the gear box 52 where gears 100, 102, like the gears 96, 98 respectively are mounted to drive the spindle through which the model 70 and work piece 68 are driven.

A vitally important feature of the present invention consists in this spindle and its attached dogs. It has long been the aim of shoe manufacturers to avoid a considerable part of the expense of the provision and upkeep of lasts by using a single heel part with a plurality of foreparts. This necessitates that the parts be absolutely interchangeable, and this requirement has impeded the achievement of commeimially practical results by any of the solutions of the problem proposed by previous inventors. It has been proposed to sever the rough block into a heel part and forepart, oin them by a bonding mechanism and then turn the last. Th is procedure, while competent to make one good separable last, does not insure that the joint surface will be placed uniformly in different lasts, since any variations in the rough blocks terminal contour and dog penetration for example affect the longitudinal position of the last in the rougl'i block. and the parts thus formed may not he interchangeable.

It has also been proposed to sever the block as above stated and turn the last parts independently. the foot contour being shaped in some definite geometrical relation to a (preferably plane) surface having a useful function in the st: such surface being generally the joint surface between the heel part and orepart. While the prior inventions along this line offer great pron'iise. I believe that furthe! improvement still possible, especially n the eliu'iiuation of one mechanical difliculty which has strongly militated against their success. In the last lathe as ordinarily constructed. the model and work are driven, one from the other, through a train of gearing in the swing (or slide) frame. A. certain f backlash is always present in such -d gives rise to such difficulties following:

When the model wheel is rolling up over the model cone. the reaction between the two crowds the model backward against its drivinggears: after the wheel passes the cone and b gins to roll down. the reaction crowds the model ahead against its driving gears. An in ccuracy in reproduction results from this shifting of the backlash from one extreme to the other. This inaccuracy is variable and more or less casual, and where a last part is being formed which is to fit other last parts formed in other operations, and on other machines, it prevents the accuracy of registration necsssary in their surface contours about the joint. This difliculty is entirely eliminated by the construction described. The model last part and the block are rigidly integrally held in relation to the same spindle, and whatever happens to one must happen to the other, as far as this difficulty is concerned, since there is no backlash between them.

The swing frame shown has other important advantages, aside from its peculiar relation to the matter of lastpart production. A difficulty which has always given trouble in last cutting, and which is avoided by the construction shown, may be illustrated as follows: Suppose the model to be a truncated circular cone, swung on its axis in the swing frame, and that the cutter and model wheel are traversed over the work and model without rotating the model and work. The point of contact of the model wheel on the model will not stay in the same plane passing through the axis of the cone since as the swing frame turns more or less to accommodate the varying diameter of the model, the point of contact will move around the model. Another way of stating the difliculty is to suppose that the model swells while the machine is motionless. The point of contact, as it moves outward from the model axis, will not stay on the same model radius. This matter, in case normal 1 :1 reproduction is being done. does no harm, because the model and work have the same treatment, but if the model and work are rotated in opposite directions in order to take care of the rightand-left question, it introduces inaccuracy. This difficulty has been dealt with in the past in two ways:

1. By providing a slide frame, which does not rotate at all; 2. By providing a swing frame of long radius of swing, so that a swing of 3 or 4 inches has small angular ma gnitude. These solutions are accompanied by characteristic disadvantages. The slide frame sluggisl'i and has too much unavoidable friction inherent in its construction. The long swing frame has a very large moment of inertia and is too flexible unless made so heavy as to cause really destructive jar. Such flexibility and ar cause unequal depth of out on model and block.

This problem and the attendant disadvantages of the heretofore known solutions are dealt with by the present invention as follows: It is only 7 inches from the spindle 56 to the axis of the bar 48, and the square bar insures great relative rigidity of parts mounted on it. The gear casings are made of aluminum, and'the mass is concentrated very largely around the axis 48. In the machine shown, of the mass of the entire swing frame, model and block is in the bar 48. The moment of inertia is very small about this axis, and the jar of reversal. of movement consequently minimized. It has proved possible to run this machine at 50 or R. P. M. with less jar than is experienced on the Gilman machine at 30 R. P. M. This enables me to secure the same rate of production as on the Gilman machine, and at the same time to shorten the feed so that the product does not have to be smoothed, so that an item of highly skilled labor is avoided.

This shortening of the radius of the swing frame of course tends to accentuate the above-described difficulty due to rotation in following work of varying diameter. This difficulty is, however, entirely removed by a feature of the construction disclosed. The gear 96 has exactly half as many teeth as the gear 98, the gears 90 and 92 are equal and the distance on centers between the shafts 48 and 5b is designed equal to the distance from the center of the shaft 48 to the center 103 of the model wheel 104 in its normal or zero position. This position is in alincment with the cutter center. If now the gears 8890 are fixed and the swing frame rotated, a radial line 106 (Fig. 11) of the gear 98 which passes through the center 103 of the model wheel will always pass through it, irrespective of the position of the swing frame. This appears from Fig. 11. Suppose the parts origin ally in the full-line position, with the angle it between the swing frame and line 48-103, and with the model radius 106 passing through the center 103. Since the triangle 481()380 is isosceles, the angle at is 902, I Let the frame swing out counterclockwise through an angle D. The gears 92 and 96 will be rotated thereby counterclockwise an angle gt) with regard to the swing frame. The gear 98 will therefore turn a clockwise angle of {,4) with regard to the swing frame and the angle at 80 made by the same radius 106 of the gear 98 will be 9() I which is the base angle of an isosceles triangle 8()481()3. The same radius 106 will. therefore continuously point to the center 103 of the model wheel 104 irrespective of the position of the swing frame.

The novel subject matter set forth in the preceding paragraph is not claimed herein, but is claimed in my continuing application, Serial. No. 284,078, filed June 9, 1928.

It will be noticed that a cross-section of the shaft 48 has one diagonal in the plane containing its axis and the axis of the spindle 56. This structure has apeculiar advantage. If there is any looseness in fit of the frames 72, 74, when they are tightened up against the model and work, they will rotate slightly and cramp on the shaft and the dogs 80 and 82 will always settle into this plane because of the double V action, no matter how loose the frames are, and their distances from the axis of the shaft 48 under normal conditions will not be substantially affected.

The model wheel 104 (see Fig. 4) is carried on a slide 106 having forward. and back horizontal movement transverse to the direction of feed of the model wheel carriage, and normally held back by the spring 107. The

forward horizontal movement is effected by rod 108 pivoted to the slide at 110, and contacting through a roller 112 with a fan board 114 pivoted on an axis at 116 and operated by a link 118 joining it to the swing frame as is well understood. Fig 4 (see also Figs. 2 and 19) shows a mechanism for irregular width grading around the periphery of the work. This mechanism is described and claimed in my application, Serial No. 429,719,

filed December 10, 1920, and will be only briefly described here. The fan board is cylindrical in form, the center of the cylinder being at the center 110 when the swing frame is in an adopted zero position, shown in dotted lines in Fig. 19 as 114 so that adjustment of the width grading factor can be made Without moving the grading slide 106. A long pinion 120 on the shaft 38 operates a gear 122 which slides along it, being mounted on the model wheel carriage, and which ca rries a cam 124. The gearing is such that the cam 124 and the model and block rotate with equal angular velocity. The cam operates a roll-(r 126 on a crank arm 128, spring held at 129, of the segment 130 which is pivotally included at 132 on the model wheel carriage. The slot shown in this segment carries a block 134 pivotally carrying the end of a. link 136, which is joined to the rod 108. The lower end of the link 136 is shown directly over the pivot 132 in Fig. 4, but can be adjusted anywhere in the segmental slot by a link 138 pivoted to a rigid arm 139 on a segment 140, pivoted at 141 and operated by a worm 142 on the shaft 144, by a handle 146 at the front of t e model wheel carriage. A dial 147, geared shaft, indicates the setting. The radii the slot in the segment 130 is equal to length of the link 156. A certain zero tion of the segment 130 corresponds i ()1\ inary width grading, which will result fr its being placed in this position and the b 134 being adj ted to the point WVith the parts as shown in Fig. 'i

roller 112 at the fan-board center 116, if

segment 130 is swung to the position where center of curvature falls on the pivot at u 'iper end of the link 136, the width will zero, irrespective of ti of the block 134. For the purpo of the pres-en application it is enough to v that the cam by rotating the segment 1130 with proper adjustment of the ilock 134 causes a continual variation in the setting of the link 108, so that the width grading function is -.s the grade adiustn'ient cyclically varied, the cyclic period being that of the rotation of the model and work. This enables me to grade lasts of two different widths with the same insole pattern, for example.

Another important feature of the invention will now be described (see Figs. 4, 10 and 19). l f width gradin is to be done, it is necessary for the model wheel to be given a special movement in order to keep it in the plane con taining the spindle 56 and the cutter center, since the horizontal width grading movement of the slide 106, if uncorrected, will carry it out of this plane. Remembering that an angle inscribed in a circle is measured by half the intercepted arc, it will be seen from Fig.

11 that it is necessary, in effect, to rotate the grading slide 106 about the zero position of the model wheel center, which is in line with the cutter center, just half as rapidly as the swing frame rotates. The mechanism for accomplishing this result is as follows Pivoted at 148 on the grading slide 106 is a lever 150 formed as a double crank, one crank on each side of the slide 106. The forward arm carries the model wheel 104, and the rear arm carries a laterally extending slide 152 rotatable about a horizontal axis 15?, (Fig. 10) on the lever 150. Mounted on a horizontal stub shaft 154 rotatable in the main. body of the model wheel carriage 18 is a slideway 156, carrying the slide 152, on one side of the slide 106, and an arm 158 on the other side. The arm 158 is linked to the fan board by a link 160, which slides along a rod 162 at the top of the fan board as the model wheel carriage moves along the bed. It is steadied by a strap 164 on the outside. As the fan board tilts in obedience to the swing of the swing frame, it turns the shaft 154 and slideway 156. As seen in Fig. 4, when the swing frame moves counter-clockwise, the fan board moves clock wise, as does the slide 156. If the width grader is set to grade up, the grading slide 106 will move out as the swing frame does. As this occurs, the parts 152156 will tilt the lever .50 clockwise and cause the model wheel to rise as moves out, but as the swing frame moves farther and farther, the slide 156 becomes horizontal and then tilts inthe opposite direction to that shown in Fig. 4, so that the model wheel, after rising for a time, begins to fall, thus always moving toward the center 80. The slideway 156 is in elfect a cam which can be shaped to produce exactly the desired movement of the model wheel.

The shape of this cam may be determined as follows. See Fig. 12 in which 0 represents the center of the shaft 48 and a represents the centerof the cutter 165 and the zero position of the center 103 of the model wheel 104. The model wheel and cutter are here shown as of circular projection, of radius approximately equal to the effective radius of the elliptical projection of the model wheel and cutter used.

Fig. 12 is drawn approximately to scale. The axis of the model and work 56 is represented at 0; (Z represents the fulcrum 148, and b the pivot 153 at the rear end of the lever 150. which is therefore adb. The radius of the model being treated is cm, and it is necessary that the point (i move down to a along the line ca, by swinging the line (all) around the point (Z, which slides along the line a?) by virtue of the ordinary width grading movement. This brings the line into the position a a! I), and the rotating slide way 156 must be such as to move the point I) to 7). The point Z: is the position of the center 0 where no correction is needed to the grading slide movement, that is, where the slideway 156 is horitech! sin ada =sin sin 5 -6 (1) The projection of ac on at is ca cos 46 1)?" cos 4 -6 and therefore I rl'n) (1-cos (,5) (g-'l)r cos l6 (:3)

e have also D7: sin %9 sin ow g 41%]? In the machine disclosed, as actually constructed,

R 1.58 inches.

n=8 inches.

79 6 inches.

=7 inches.

]v/I.=4.75 inches. whence by (5) hen the center 0 is at In, that is when 9' 0, no correction to the movement of the grading slide is needed. Then by (4) and k i .1. \I/ M 2 Q 9 gr 3.17 Now a width grade of 7 sizes from a mens whence (6) For the special condition above noted, if 9 12, 1 26, which is a greater radius than is found anywhere on a mens #7C. This means that most last turning even when grading will be done with the center 0 between 70 and a; that is that 6 is generally negative in last turning and when positive, is small. Fig. 12 has however been drawn as if the model were much larger. in order to avoid crowding of the lines in the tad neighborhood.

Now obviously. if we could drop out the (pa) (icos (/1) term in (3) we would have simply from (2) and (3) =tan bbe=- tan 9 x n and if we make the special assumption that :2, as in the described machine, We have tan bbe=tan 9 (9) for any position of Z)". In other words, the slidcway 156 could be straight, and its rotation from the horizontal position (which corresponds to the position of c at is) would equal the angle 9. In still other words, if the swing frame be swung to a certain position 9 and held there, and the model be swelled or shrunk and be followed by the model wheel, by suitable continuous variation of the width grader setting, along the line ma, the pivot 7) (153) would travel on a straight line Z17), whose position depends only on the value of 9.

'laking the last matter first, the maximum numerical value of 6 is 7008 in Fig. 12, so that the model axis lies on the face of the model wheel. Putting r=0 in (4) we find 0 to be "26 42. This condition is approximated in cutting the upper surface just behind the toe of some types of lasts. Now

1 tan (13 21) .944

and therefore a maximum error of about 5% in the slope of the slideway 156 is involved in this approximation. Furtl'ier. this maximum value of 9 corresponds to the condition where the grading movement of the model wheel is very small so that a correspondingly small actual error in the cutting actually results.

In the matter of (1 00s we proceed as follows: For any given value of 6, gr becomes a constant, by (4) and the value of sin b depends only on 1)), by This will be a numerical maximum when r is a tan [/06 2 tan 6=tan 6(1tan #7+G gives a grading factor of about 1.2. minimum since r is constant; and r is a 120 minimum when 9 is a maximum, for the same reason. We have suggested 9 12 as the maximum grade in last cutting, and we then have,

whence, from (1) after solving for yr:

14 sin (9+I )1.58

so that the (1-cos I term in (3) amounts to only .0005 inch at most; the maximum horizontal error in the position of the model wheel center is half that amount, and is utterly negligible; and a: is therefore given within the limits of accuracy in woodworking by r12=(g1)r cos 9 The error in 3 due to our approximation may be found as followsz'From (2) the true 7/ 1S 7 =2 (g-1)r sin go (14) and the approximate 7 given by the machine 1s y rr tan 6 (9-1)? cos {s6 tan 6 The error in y is the difference between (15) and (14) or For any definite value of 6, we have as before, the greatestvalue of (19 at 9 12. We then derive, in the same way as in the case of (11) The maximum value of this expression occurs at -201- and is "0.0015 inch. The vertical error in the position of the model wheel center is one half as great.

Thus the errors in the placing of the model wheel, when g runs from O to 1.2 are less than 0.0003 inch horizontally and 0.0008 inch vertically, assuming the slideway 156 to rotate exactly with the swing frame. Exact relationship of-this kind is of course procurable by a rack and pinion connection, but the link motion shown produces quite satisfactory results, as would be obvious from the fact that the angle I does not exceed 0 36 in last cutting.

The investigation for a diminishing grade need not be given here. The analysis is quite similar, and the exact performance of the machine under all circumstances can be deduced from equations The artifice of placing the center 1033 behind the center 48 substantially diminishes the errors of the machine. If these centers were in the same vertical the error would in crease continually as 0 moved from s. \Vith the machine as it is, the error increases as 0 moves from s and then diminishes again as c approaches is.

A directly motor driven cutter is shown at 165. In view of the fact that the axis of the model wheel and cutter are inclined at about 30 with and toward the direction of feeding travel (this feature is explained in United States Letters Patent Nos. 1,137,117 and 1,330,841, granted on the applications of F. S. Buck), it is necessary to provide that the tipping of the lever 150 shall not carry the axis of the model wheel out of horizontality. This is accomplished by pivoting a link 166 in line with the center 103, on the effective end of the lever 150. This link is joined to the slide 106 by a second link 1.67, equal in length to the distance 103148, and with its inner end located vertically below the point 148 at a distance equal to the effective length of the link 166. The link 166 must therefore always remain. vertical. The model wheel spindle projects from the side of the link 166 at an angle of 30, as is well shown in Fig. 2, and will always remain horizontal.

The disclosed machine is equipped with a mechanism for stopping the spindle 56 in the same orientation to facilitate the convenient insertion and removal of work. The pnlley 40 is rotatably mounted on the shaft 38, and is connected with it by a laterally sliding clutch (not shown). This clutch is operated by a lever 168 by pushing its outer end outward, which is accomplished by the following mechanism: A bell-crank lever 169 (see Fig. has a notch in its upper surface which catches a pin 170 on the swing-frame when the frame is pulled out by the operator. It also has another notch 172 in which rides a finger 174 of the rod 176, pivoted to a bell crank 178 at the back of the machine( Fig. 3) This hell crank carries pivotally at 180 a rectangiiilar bar 181. This bar has a bevel 182 which is at an angle with the surface seen in the plane of the paper and with the lefthand surface perpendicular to the plane of the paper in Fig. 3. hen the swing frame is pulled out it drags on the finger 174 and pulls it out to the notch 172. This pushes down the bar 181 until the bevel 182 contacts with the clutch lever 168 (but does not throw it). A little pinion (not shown) on the shaft 38 drives a gear 184 at the same angular velocity as that of the spindle 56 in the swing frame. A cam 186 mounted on the gear 184 thrusts grading lever 1.90 linked to the carri: by an tl(l]llt-l'ttll)l(. link 192 and pivoted or the mirriagc 18.

A special. fixture is shown in Fig; l to tit a definite length grading; prohlem. The block 1941-. instead of heme adjusted as m'dinarily, is provided with tour studs 1%. An arm 198 is mounted at an angle with the vertical on a block 200 on the carriage 2 The lilock adjustable along the carri; 5e hy a screw 202. and the arm 198 carries tour corresponding studs 2041. The mounting ot the link 192 on any pair of corresponding studs adjusts the machine for a predetermined length grading; problem.

A pretcrred arrangement of. the grading mechanisms shown in Fig. 8. The model wheel carriage 18 carries an apron 206 on which is mounted a shatt 208 geared to the shaft 1 14 at 210, and to the lever 21.2 at 2l-it-. The lever is pivoted at 213. lrlovement oi the handle 1:16 theretore will operate a pointer 216 on the lever The apron also carries a three-armed lever 218 pivoted at 219 having); a pointer 220 on one arm, a g ar connection 222 with a shaft on another arm, and having a link 22G connecting; the third arm 228 with the block 200. he length grading mechanism here is not automatic at all, the distance between the carriages 18 and 22 being fixed except when being varied by means of the handle 228. on the shaft 224:. Curves 230, 232 drawn on a chart 234i: fixed on the front of the machine Frame serve the operator as guides for continuous control oi the graders While the cutting; is being done.

This chart, may be advantageously formed as follows (Fig. 13); a board or table 286 having a graduated rail 238 graduated in inches alone one edge. is provided with two template holes 2 10, corresponding to the holes 242 in the front of the machine. The chart paper is pinned by these holes in each ca... A slider 244; is provided to move hack and torth along the guide rail. The edge 246 oi? the slider is a nearly circular are having the same orientation and vertical relation to the holes 240 as that ol the path of the pointer 220 to the holes 242. When the pointer is moved With the carriage 22 at rest. (The carriage 18, on which the pointer is pivoted. moves slightly Willi the adjustment, that the path of the pointer in space is nota perfect circle.) The edge 2% of this slider is graduated, the units representing for example, a 1/24 inch alteration in the distance between the carriages 18 and 22. The zero point 248 represents the position of the pointer when the carriages are so adjusted that the centers of the model Wheel and cutter will simultaneously aline with the axial centers 250 of the itaces of the dogs ('36 (Fig. 6). It now a horizontal line 252 be drawn on the chart opposite this zero mark and the pointer 220 seton it and left there, the model Will be exactly copied as far as longitudinal dimensions are concerned. Suppose that the model measures 12 inches over all, divided into two sections of 10 inches and 3 inches from the ends to the axial point in the joint surface (c u'responding; to the point 250 in Fig. 6, neglecting the position of the joint plate). Suppose that the thickness of the model wheel and cutter is 1 inch. Then the model Wheel has to travel 10 and 3 inches, respectively. in cutting the forepart and heel part. The end 25 1 of the slider is set at 10 on the scale 238, and a line 2535 drawn down alon'" he edge 2% on the chart paper. The slider then moved until the point 254 comes opposite the 3 graduation of the scale 23.8 am a mark 256 made at the intersection Oil the edge 2&6 and the line 252. Suppose now that We want to make a last Which is of :tectirel v 1/3 inch longer than the model. Draw a line 258 from the point 256 to the 1/ 8 inch point on the line 255. It now the paper he mounted in the machine and the pointer 220 kept on the line 258 by the 0peratoi"s use of the handle 228, the ordinary length grading operation will be accomplished. The elongation of the heel part corresponding to this operation is represented by the distance 249.

Supj iose now :or example that we Want to cut a last helon ing to a. set in which all the ioreparts ot a group lit the same standard heel part; in which a group of lasts will have the same insole pattern. and a group of lasts Will have the same toe tip, for example, for the general purpose of standardizing shoe manutmrtnre and reducing its expense. Suppose that our last in order to lit the group insole actually to he 9/24l inch longer than the model. While having the longitudinal foot room of a last 8/21 inch long Suppose al o that. it is to have a standard toe tip which is just like the model tip. Draw a line 2 on the chart parallel to the. line 252 and passing" through the +9/2 l )Olllt of the line 255. and make. it as long as the standard toe tip. a line 262 dropping rapidly and easily to the line 258. Suppose now that the standard heel part to he used with the set to which this torepart belongs is. instead oi 3 inches'tthe elongation 249, to he actually 3 inches l the elongation 264 and that it to he termed by regular grading from the model heel part. The line 266 corresponds to the regular grading of this heel part. from the model heel part. This line 266 is extended tar enough beyond the zero of the scale 238 to cover the point 268 (Fig. 6) and a line 270 is drawn to blend the line 258 into the line 266. If now the pointer 220 be made to follow the curve 260-262258-270266, the forepart will fit the standard tip and insole, and will be graded in the instep, where fit is important, strictly according to the ordinary system, and will fit the heel part common to the set at its rear end. The line 260 copies themodel. toe tip exactly. the line 258 stretches the ball-instep portion in the proper fashion, and positions it in proper relation to the heel end 256; the line 270 shortens the model just behind the instep, to allow for the oversize heel part; and the line 272 grades the part 11st in front of the joint so that it will justfit the heel part.

The width grading problem may be similarly solved. The tip length should be graded directly from the model. Suppose the ball" and instep portion is to be graded up 1/4 inch (in perimeter) and that the standard heel part is constructed as for a last whose ball-instep portion is being graded up 5 16 inch. The other edge 274 of the slider 244 is formed on the curve traced by the pointer 216 when the carriage 22 is motionless, and the edge is graduated. The width grader is automatic, and all that the handle 146 does is to change the grading factor so that the scale 274, if graduated in units of girth change, as is convenient, will vary with the model used. lVe will suppose that We have a scale 274 graduated in 1/16 inch changes in perimeter for the model being used.

- Suppose the worm at 214 to be such as to throw the pointer 216 up when grading up, and. that the parts are designed so that the same line 252 is the zero width grade line. 1V ith the end of the slider at 10 on the scale 38, mark the point 276 at the intersection of the line 252 and edge 274. Move the slider along the length of the toe tip to 277 and mark a point 278 at the 4/16 point of the scale 274. and draw a line 280 from the point 278 parallel to the line 252. Draw the line 282 from the line 252 at 277 to blend into the line 280. Then move the slider until its end 254 at the zero of the scale 238, putting the edge 274 at 284. Draw a line 286 through the 5/16 point of the scale 274, and blend theline 280 into the line 286 by a line 288 just before the point corresponding to the point 268 is re a ch ed By the use of such a chart in connection with the equipment shown in F 8, the operator is enabled to cut lasts having such peculiar and miscellaneous characteristics as those described, and the operation is rendered so simple as to require little skill on his part.

Another important feature of the present invention consists in an accurate pantophic width grading mechanism with an equicrescent setting scale.

lVidth grading mechanisms as found in the machines heretofore in use are subject to a serious fault, arising as follows: In width grading the successive members of a set of lasts increase in girth by constant amounts. If the radius of the model is r, and the magnification factor is f], the swing frame must be moved a distance from the face of the cutter and the model wheel must be advanced r "1) r from its zero position to hold it there. The fan board moves proportionally to the swin fran'ic, so that the width grader feeler setting is proportional to M=Qj 9 9 We can assume the factor of proportionality to be unity without loss of generality. In the following table are shown the ball girth measurements of av set of 13 lasts, the factors 9 necessary to produce them from a. 7Cmodel, and the width grader settings,

This would increase the grader setting 1/34 per size. The 7 AAAAA setting would. then be -6/34 and the 7 EEEEE setting would be +6/34. Now 6/34 is numerically smaller than 6/28, by more than 1/6 of the whole setting, indeed, the setting for the 7 AAAAA is just about what it ought to be for that 7 AAAA, so that on the 7 AAAAA the model is not shrunk enough. Also 6/34 is larger than 6/40 (which about 5/34) so that on the 7 EEEEE the model is swelled too much. At the extremes the settings would be about a size out, each way. To correct this, the fan board 114 was backed otf each side of its axis 116' (see Fig. 18) so as to present a list wedge to its feeler 112. As the feeler was moved either way from the zero position, it would let the model. wheel settle back from the swing frame by an amount constant for 

